Interpretive Summary: Research has demonstrated that changes in protein level and/or fatty acid profiles in diets fed spawning fish can have an effect on reproductive success. Modifications made to diets differ dramatically, along with timing of the dietary regime, and likewise significant differences have been found for the effect of these diets on spawning fish. To study this effect we evaluated 3 different families of rainbow trout reared on diets containing either fish meal/fish oil, plant meal/fish oil, or plant meal/plant oil in their formulation. It was determined that the fish grew better on the fish meal/ fish oil diet and that the fatty acid profiles of the eggs spawned from the fish matched that of the fatty acids found in the oil included in the diet. There were also diet and family effects found in this study when correlations were determined with the expression of specific metabolic genes.

Technical Abstract:
To determine the effects of plant protein and oils on spawning rainbow trout an experiment was set up to examine 3 distinct families fed the following diets: 1) fish meal and fish oil; 2) plant meal and fish oil; 3) plant meal and plant oil. The fish were fed the diets for one year through spawning. The effects of the diets on the growth of the fish showed that the fish on the fish meal and fish oil diets were heavier were higher specific growth rates and lower feed conversion ratios. In the eggs from spawned fish it was noted that the fatty acid profile found in the eggs was typical of that found in the diet of the fish with the eggs from the fish reared on the plant meal and plant oil diet having very low levels of 20:5 and 22:6. The diets also appeared to affect egg size with eggs from the fish reared on the fish meal and fish oil diets giving significantly larger eggs. Finally it was noticed that there were significant diet and family interactions for the expression of the gene '6 dehydrogenase.